The present invention finds primary utility in the field of wireless communications. More particularly, the present invention relates to an antenna assembly suitable for wireless transmission of analog and/or digital data in a single or multiple frequency band antenna system.
A variety of prior art antennas are currently used in wireless communication devices. One type of antenna is an external half wave single or multi-band dipole. This antenna typically extends or is extensible from the body of a wireless communication device (WCD) in a linear fashion. While this type of antenna is acceptable for use in conjunction with some WCDs, several drawbacks impede greater acceptance and use of such external half wave single or multi-band dipole antennas. One significant drawback is that the antenna is typically mounted at least partially external to the body of a WCD which places the antenna in an exposed position where it may be accidentally or deliberately damaged, bent, broken, or contaminated.
Furthermore, due to the physical configuration of this class of omni-directional antenna, optimizing performance for a particular polarization and/or directional signal is not an option. That is, these types of prior art antennas are relatively insensitive to directional signal optimization or, said another way, these types of prior art antennas can operate in a variety of positions relative to a source signal without substantial signal degradation. This performance characteristic is often known as an xe2x80x9comni-directionalxe2x80x9d quality, or characteristic, of signal receipt and transmission. This means that electromagnetic waves radiate substantially equally in all directions during transmitting operations. Such prior art antennas also are substantially equally sensitive to receiving signals from any given direction (assuming adequate signal strength). Unfortunately, for a hand held WCD utilizing such a prior art antenna, the antenna radiates electromagnetic radiation toward a human user of the WCD equipped with such an antenna as there is essentially no front-to-back ratio. For reference, the applicant notes that for multi-band versions of prior art types of antenna, the external half wave single or multi-band dipole antenna (i.e., where resonances are achieved through the use of inductor-capacitor (LC) traps), signal gain on the order of approximately a positive two decibels (+2 dBi) are common and expected.
In addition, due mainly to the inherent shape of such prior art antennas, when operating they are typically primarily sensitive to receiving (and sending) vertical polarization communication signals and may not adequately respond to communication signals that suffer from polarization rotation due to the effects of passive reflection of the communication signals between source and receiver equipment. Furthermore, such prior art antennas are inherently inadequate in sensitivity to horizontal polarization communication signals.
Another type of prior art antenna useful with portable wireless communication gear is an external quarter wave single or multi-band asymmetric wire dipole. This type of antenna operates much like the aforementioned external half-wavelength dipole antenna but requires an additional quarter wave conductor to produce additional resonances and, significantly, suffers the same drawbacks as the aforementioned half wave single band, or multi-band, dipole antenna.
Therefore, the inventor recognizes and addresses herein a need in the art of WCD antenna design for an antenna assembly which is compact and lightweight, that is less prone to breakage and has no moving parts (which may fail, become bent, and/or misaligned), and, which utilizes the available interior spaces and structure of a WCD to achieve a more compact final configuration.
There is also a need for a multi-frequency antenna assembly which is able to receive and transmit electromagnetic radiation at one or more preselected operational frequencies.
There is also a need in the art for a deformable antenna resonator which is equally responsive to a variety of different communication signals having a variety of polarization orientations.
There also exists a need in the art for an antenna assembly which is compact and lightweight and which can receive and transmit electromagnetic signals at one or more discrete frequencies and which antenna assembly can be tuned to one or more frequencies.
The invention herein taught, fully enabled, described and illustrated in detail herein is a multiple band antenna assembly for use in a wireless communication device (WCD) which meets the shortcomings of the prior art. The inventive antenna assembly of the present invention includes a deformable resonator element disposed on a dielectric resonator support substrate and operatively electrically connected to both an RF signal line and to a ground plane associated with a WCD. The resonator element comprises a substrate which supports a conductive element or portion.
The deformable substrate of the resonator element is preferably sufficiently flexible to permit fabrication of a variety of antenna shapes and configurations depending on the available space within a WCD. The flexibility of the substrate allows for a variety of shapes for the resonator element to be coupled to WCDs at a variety of locations with respect to the WCD, including discrete single or multiple locations disposed in the interior, the exterior, and/or located at discrete locations along the periphery of electronics disposed within a portion of the housing of the WCD. Preferably, the resonator element is curved or arcuately shaped, however, other configurations are possible and clearly within the purview of those skilled in the art to which the present invention is directed.
The resonator element also includes a conductive portion which may take several forms in different embodiments of the present invention. In one preferred embodiment, the conductive portion is a wire member which is coiled about the flexible resonator support substrate. In another embodiment, the conductive portion includes at least one trace of electrically conducting material spanning the resonator element and contacting a conductive layer. In another preferred embodiment, the conductive portion includes an array of deposited conductive material in contact with a continuous conductive layer. All of the preferred resonator embodiments of the present invention include a discrete electrical connection location which is operatively coupled to separate signal and ground lines. The position of the discrete electrical connection location may be varied depending upon the frequency ranges and performance requirements for a given application or a particular configuration or style of WCD.
The resonator element is preferably provided with a generally planar bridge, or support, element which mechanically supports and electrically couples the resonator element to the ground plane of reduced electrical potential preferably disposed on or in a printed wiring board of a WCD. The bridge or support element is formed of dielectric material and includes a first edge portion which helps support and maintain the resonator element in a desired, preferably arcuate, configuration. In one embodiment, the support element also has an edge portion with a conductive strip portion which is used to operatively connect the support element to a ground plane.
The antenna assembly comprises a dielectric resonator support element and an electrically conducting resonator element and an electrical connector element electrically coupling the resonator element to the ground plane of the WCD. The resonator support element may itself support the resonator element or may include another a preformed resonator support substrate which in combination with a dielectric bridge member supports the resonator element, respectively, or supported directly by a substrate having discrete electrical components coupled thereto (i.e., the printed wiring board, or xe2x80x9cPWBxe2x80x9d) providing function to the overall operation of a WCD.
In one preferred embodiment, the resonator element includes an outwardly facing conductive portion with a plurality of inwardly facing discrete conductive portions electrically coupled thereto. More specifically, the outwardly facing portion of the resonator element may comprise an elongated band or sheet of electrically conductive material, and the inwardly facing conductive portions comprise a plurality of transverse bands of electrically conducting material electrically coupled to and spaced from the outwardly facing portion. Preferably, the flexible resonator support substrate is in a supporting relation to the outwardly and inwardly facing conductive portions and is comprised of a material (such as laminated epoxy, cyanate ester, polyimides, PTFE, etc.) having dielectric properties. The resonator element may be formed into a variety of shapes, for example, a xe2x80x9cC-shapedxe2x80x9d member, and the resonator support member may have a xe2x80x9cD-shapedxe2x80x9d member that when configured as taught herein share a common curvature, or cooperative supporting orientation or configuration. With respect to the xe2x80x9cdeformablexe2x80x9dcharacteristic of the resonator member, said characteristic is useful primarily during manufacture of the antenna assembly of the instant invention and does not contribute meaningfully to any functionality of the resulting antenna assembly.
In one embodiment, an electrically conducting connector element is preferably located adjacent the dielectric bridge member and the connector is bifurcated (e.g., shaped with elongate dual fork features) with the major end configured to operatively connect to the resonator element and the minor ends configured to operatively connect to the ground plane of a WCD and a radio frequency (RF) input/output signal feed, respectively.
The dielectric bridge member may optionally support an electrically conducting area or patch electrically coupled to the ground plane of the WCD thereby extending the effective electrical length of the ground plane. Generally, the dielectric bridge member and the flexible resonator support substrate are comprised of material having sufficient dielectric properties and may vary in thickness, shape, size and composition but generally are intended to provide mechanical support to the electrified components of the WCD, including the antenna assembly. In one embodiment of the present invention an integrated monolithic substrate member performs all the functions of the first and dielectric bridge member described herein in reference to preferred embodiments.
Generally, the dielectric bridge member and resonator support member presents a substantially planar surface including opposing major support surfaces and a support edge designed to conform to support the deformable flexible resonator support substrate. The support edge is provided with a plurality of stand-offs which enable the dielectric bridge member to contact the flexible resonator support substrate in a non-conductive relation. The downwardly facing edge includes a pair of downwardly extending tabs through which the antenna assembly may be attached to the printed wiring board of a WCD.
The resonator support substrate and the dielectric bridge member are connected to each other in a preferably orthogonal configuration and in combination with the resonator element electrically coupled to the printed wiring board and attendant ground plane of a WCD thus forming the antenna assembly.
As will be appreciated by those of skill in the art to which the invention is directed, the size, shape, physical configuration, electrical and frequency performance characteristics of the antenna assembly will depend in part on the particulars of a given WCD design iteration in view of desired operating frequency (or frequencies), interior dimensions, electrical power constraints, composition of WCD components, and the like. Further, the antenna assembly may be coupled to a WCD at a variety of locations, including the interior, the exterior, within a portion of the housing of the WCD itself, and may be coupled via a suitable antenna interface outlet using conventional components.
It is an object of the present invention to provide a compact antenna assembly designed to be incorporated into a variety of WCDs by conforming to diverse geometries within the interior space of such devices.
It is another object of the present invention to reduce the potential for damage and/or breakage of traditional antenna designs by reducing external parts to a minimum and firmly mounting antenna assembly components to pre-existing structure of compact WCDs.
It is another object of the present invention to simplify construction of an antenna assembly according to the present invention through use of known and traditional antenna, semiconductor, and electronic device fabrication techniques and technologies for production of multiple frequency band antennas.
Accordingly, another feature of the present invention is to provide a compact and effective family of designs for an antenna assembly operable in more than one frequency band.
In addition, with respect to said family of multi-frequency antenna designs, a further feature of the present invention is a single dedicated discrete electrical connection location selectively defining each frequency band while commonly electrically coupled at a single contact location to both the RF signal line and the associated ground plane.
Yet another feature and advantage of the present invention relates to a family or class of antenna assembly designs capable of conforming to existing structure of a compact WCD into which it is incorporated, including incorporating all components and electrical connections for the antenna assembly during original manufacture of the WCD on a common dielectric substrate member or members supporting the electrical circuit components of the WCD.
Still another feature of the present invention relates to the several effective antenna assembly embodiments thereof having no portion thereof external to the WCD and having no moving parts subject to breakage, physical degradation or other loss.
It is an additional object and feature of the present invention to provide an antenna assembly which may be incorporated into a WCD and wherein the resonating element portion of the antenna assembly is tunable over a range of discrete frequencies.
These and other objects, features and advantages will become apparent in light of the following detailed description of the preferred embodiments in connection with the drawings. Those skilled in the art of WCD antenna design will readily appreciate that these drawings and embodiments are merely illustrative and not intended to limit as to the true spirit and scope of the invention disclosed, taught and enabled herein.